What is meant by saying time has a direction and how would one know if it were reversed?

Question

What is meant by saying time has a direction and how would one know if it were reversed?

Answer 1

time is a measurement, used by humans and relative to life.

past,present,future.

i haven't had a physics class though, so they may have a different meaning.  

when i was in school average meant average and mean meant not nice,...,...,

Answer 2

Only one second (Now!) is real.  The past is gone forever and the future always awaits its arrival.  If time were reversed, the earth would spin in the opposite direction and puke would leap from the floor into a sick persons unsuspecting mouth, etc.

Answer 3

It's Simple. More probable events tend to occur in the future, less probable events tend to occur in the past.

This is the ONLY distinction between past and future in Physics, and this answer encompasses everything anyone else has to say about entropy (but in a way the average Joe ought to be able to understand).  

Answer 4

There is a concept in thermodynamics called entropy.

Entropy always increases.

The arrow of time point always to the direction of increasing entropy.

If you find entropy decrease, then you know time has been reversed.

Answer 5

You might like to read this: An Experiment with Time by J. W. Dunne, first published in 1927.

http://en.wikipedia.org/wiki/An_Experime...

Answer 6

It has direction : from past events to future events

so it is described as a dimension.

See arrow of time

irreversibility: heat doesn’t flow spontaneously from cold objects to hot ones, we can turn eggs into omelets but not omelets into eggs, ice cubes melt in warm water but glasses of water don’t spontaneously give rise to ice cubes. These irreversibilities are summarized by the Second Law of Thermodynamics: the entropy of a closed system will (practically) never decrease into the future.

Answer 7

If time were reversed the entropy of a closed system would decrease-true. But far worse than this is that cause and effect would be meaningless in a fixed frame of reference. Travelling backward in time, so to speak, would give the observer prior knowledge of what to them would be future events and they could takes steps to avoid them thereby creating a paradox.

Answer 8

well, time dosn't really have a direction but instead a path of occurences that take place. but in order for time to have a "direction" would also imply fate. but in a choose your own path sort of theme, one track of time(occurences) would be taking place while multiple others would be taking place and when a major occurence approached the next path taken would all depend on what actions are taken. you stand and whach a man get hit by a car and the track continues on with you unharmed and a man under some heavily filthy treads. but if you were to push him out of the way and you yourself were hit then the track would split off into every sort of possibility that could have happened and play itself out. but all that sounds crazy.

and if time were reversed we wouldnt know. we would just continue on with no recollection that we are actually in the past and have already lived in the future.

here's some litterature i found that might help

enjoy

http://jcbmac.chem.brown.edu/scissorsHtm...